# Learning Noise via Dynamical Decoupling of Entangled Qubits

**Authors:** Trevor McCourt, Charles Neill, Kenny Lee, Chris Quintana, Yu Chen, Julian Kelly, V. N. Smelyanskiy, M. I. Dykman, Alexander Korotkov, Isaac L. Chuang, A. G. Petukhov  
**arXiv:** [2201.11173](https://arxiv.org/abs/2201.11173)  
**Date:** 2022-01-26  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2201.11173v1/

## Key points

- Study title: "Learning Noise via Dynamical Decoupling of Entangled Qubits"
- Authors: Trevor McCourt, Charles Neill, Kenny Lee, Chris Quintana, Yu Chen, Julian Kelly, V. N. Smelyanskiy, M. I. Dykman, Alexander Korotkov, Isaac L. Chuang and A. G. Petukhov
- Focus on characterizing noise in entangled quantum systems from many-body effects involving multiple degrees of freedom
- Development and implementation of multi-qubit dynamical decoupling sequences to understand noise during two-qubit gates
- Experimental setup with superconducting system consisting of Transmon qubits with tunable couplers
- Identification of noise patterns aligning with flux fluctuations in the coupler impacting both qubits simultaneously
- Different impact of noise on qubits compared to single-qubit dephasing effects
- Observation of distinct steps in decoupled signals indicating non-Gaussian noise characteristics within the system
- Importance of developing strategies to mitigate noise effects for advancing quantum computing technologies

## Summary

In the study titled "Learning Noise via Dynamical Decoupling of Entangled Qubits," authors Trevor McCourt, Charles Neill, Kenny Lee, Chris Quintana, Yu Chen, Julian Kelly, V. N. Smelyanskiy, M. I. Dykman, Alexander Korotkov, Isaac L. Chuang and A. G. Petukhov delve into the challenging task of characterizing noise in entangled quantum systems that arises from many-body effects involving multiple degrees of freedom. This noise presents a significant obstacle in the realm of quantum computing where the performance of two-qubit gates is crucial. To address this issue, the researchers develop and implement multi-qubit dynamical decoupling sequences aimed at understanding the noise that occurs during two-qubit gates. Their experimental setup involves a superconducting system consisting of Transmon qubits with tunable couplers. Through their observations they identify noise patterns that align with flux fluctuations in the coupler—a phenomenon that impacts both qubits simultaneously and introduces disturbances in their entangling parameter. Interestingly,the impact of this noise on the qubits differs significantly from well-understood single-qubit dephasing effects. Moreover,the researchers note distinct steps in the decoupled signals,suggestingthe presence of non-Gaussian noise characteristics within their system. This research sheds light on the complex nature of noise in entangled quantum systems and highlights the importanceof developing strategies to mitigate its effects for advancing quantum computing technologies. The findings contribute valuable insights to ongoing efforts aimed at improvingthe performance and reliabilityof quantum information processing systems amidst challenging environmental influences.